New Covid cases mostly among unvaccinated
Published: 04:12 PM,Dec 25,2021 | EDITED : 10:12 AM,Dec 26,2021
A random study conducted by the World Health Organisation (WHO) has identified that the vast majority of current infections and Covid-19 cases are in unvaccinated people and vaccinated people are free from easy infection thanks to the two doses of Covid-19 19 vaccine and the booster dose.
In the observations made by the WHO with the support of the Strategic Advisory Group of Experts (SAGE) on Immunisation and its Covid-19 Vaccines Working Group, it said breakthrough infections among vaccinated persons are mostly less severe than those in unvaccinated persons.
'Booster doses are administered to a vaccinated population that has completed a primary vaccination series - currently one or two doses of EUL (WHO Emergency Use Listing) Covid-19 vaccine depending on the product- when, with time, the immunity and clinical protection has fallen below a rate deemed sufficient in that population,' said Dr. Tedros Adhanom Ghebreyesus, Director-General of WHO at an online press briefing.
He further added that the objective of the booster dose is to restore vaccine effectiveness from that deemed no longer sufficient. 'Additional doses of a vaccine may be needed as part of an extended primary series for target populations where the immune response rate following the standard primary series is deemed insufficient. The objective of the additional dose in the primary series is to enhance the immune response to establish a sufficient level of effectiveness against disease.'
In particular, immunocompromised individuals often fail to mount a protective immune response after a standard primary series, but also older adults may respond poorly to a standard primary series with some vaccines.
He has further called for a moratorium on booster vaccination for healthy adults until the end of 2021 to counter the persisting and profound inequity in global vaccine access. While many countries are far from reaching the 40 per cent coverage target by the end of 2021, other countries have vaccinated well beyond this threshold, already reaching children and implementing extensive booster vaccination programmes. Globally about 20 per cent of Covid-19 vaccine doses, daily, are used for booster or additional dose vaccination.
A recent systematic review and meta-regression analysis on the subject conducted across the four Covid-19 vaccines, it's shown that vaccine effectiveness against severe Covid-19 decreased by about 8 per cent (95 per cent confidence interval, that is 4-15 per cent) over a period of 6 months in all age groups. In adults above 50 years, vaccine effectiveness against severe disease decreased by about 10 per cent (95 per cent) over the same period. Vaccine effectiveness against symptomatic disease decreased by 32 per cent (95 per cent 11 – 69 per cent) for those above 50 years of age.
He further noted that an increased risk of reinfection was reported in England, the, as well as a growing trend of reinfection cases in Denmark and Israel, can be potentially attributed to immune evasion against Omicron.
'Omicron variant had been identified in 110 countries across all six WHO Regions. Current understanding of the Omicron variant continues to evolve as more data become available. This technical brief provides updated early evidence on key aspects of Omicron related to transmission, severity and impact on interventions such as diagnostics, therapeutics and vaccines, and outlines a set of priority actions for Member States.'
In the observations made by the WHO with the support of the Strategic Advisory Group of Experts (SAGE) on Immunisation and its Covid-19 Vaccines Working Group, it said breakthrough infections among vaccinated persons are mostly less severe than those in unvaccinated persons.
'Booster doses are administered to a vaccinated population that has completed a primary vaccination series - currently one or two doses of EUL (WHO Emergency Use Listing) Covid-19 vaccine depending on the product- when, with time, the immunity and clinical protection has fallen below a rate deemed sufficient in that population,' said Dr. Tedros Adhanom Ghebreyesus, Director-General of WHO at an online press briefing.
He further added that the objective of the booster dose is to restore vaccine effectiveness from that deemed no longer sufficient. 'Additional doses of a vaccine may be needed as part of an extended primary series for target populations where the immune response rate following the standard primary series is deemed insufficient. The objective of the additional dose in the primary series is to enhance the immune response to establish a sufficient level of effectiveness against disease.'
In particular, immunocompromised individuals often fail to mount a protective immune response after a standard primary series, but also older adults may respond poorly to a standard primary series with some vaccines.
He has further called for a moratorium on booster vaccination for healthy adults until the end of 2021 to counter the persisting and profound inequity in global vaccine access. While many countries are far from reaching the 40 per cent coverage target by the end of 2021, other countries have vaccinated well beyond this threshold, already reaching children and implementing extensive booster vaccination programmes. Globally about 20 per cent of Covid-19 vaccine doses, daily, are used for booster or additional dose vaccination.
A recent systematic review and meta-regression analysis on the subject conducted across the four Covid-19 vaccines, it's shown that vaccine effectiveness against severe Covid-19 decreased by about 8 per cent (95 per cent confidence interval, that is 4-15 per cent) over a period of 6 months in all age groups. In adults above 50 years, vaccine effectiveness against severe disease decreased by about 10 per cent (95 per cent) over the same period. Vaccine effectiveness against symptomatic disease decreased by 32 per cent (95 per cent 11 – 69 per cent) for those above 50 years of age.
He further noted that an increased risk of reinfection was reported in England, the, as well as a growing trend of reinfection cases in Denmark and Israel, can be potentially attributed to immune evasion against Omicron.
'Omicron variant had been identified in 110 countries across all six WHO Regions. Current understanding of the Omicron variant continues to evolve as more data become available. This technical brief provides updated early evidence on key aspects of Omicron related to transmission, severity and impact on interventions such as diagnostics, therapeutics and vaccines, and outlines a set of priority actions for Member States.'